U.S. patent application number 12/957715 was filed with the patent office on 2011-06-16 for wind turbine rotor blades with enhanced lightning protection system.
This patent application is currently assigned to GENERAL ELECTRIC COMPANY. Invention is credited to Peter James Fritz, Richard Hardison.
Application Number | 20110142644 12/957715 |
Document ID | / |
Family ID | 44143133 |
Filed Date | 2011-06-16 |
United States Patent
Application |
20110142644 |
Kind Code |
A1 |
Fritz; Peter James ; et
al. |
June 16, 2011 |
WIND TURBINE ROTOR BLADES WITH ENHANCED LIGHTNING PROTECTION
SYSTEM
Abstract
A wind turbine rotor blade includes a plurality of lightning
receptors configured along either or both of the pressure side or
suction side of the blade. At least one looped lightning conductive
circuit is provided, with the lightning receptors configured in
communication with a respective lightning conductive circuit. The
lightning conductive circuit has terminal ends that extend through
the root for connection of each terminal end with a grounding
system within the wind turbine. The looped lightning conductive
circuit provides a redundant path to each lightning receptor for
conducting a lightning strike to ground.
Inventors: |
Fritz; Peter James;
(Greenville, SC) ; Hardison; Richard; (Greenville,
SC) |
Assignee: |
GENERAL ELECTRIC COMPANY
Schenectady
NY
|
Family ID: |
44143133 |
Appl. No.: |
12/957715 |
Filed: |
December 1, 2010 |
Current U.S.
Class: |
416/146R |
Current CPC
Class: |
F05B 2270/1074 20130101;
Y02E 10/722 20130101; F03D 1/0675 20130101; Y02E 10/72 20130101;
H02G 13/00 20130101; Y02E 10/721 20130101; F03D 80/30 20160501 |
Class at
Publication: |
416/146.R |
International
Class: |
F03D 11/00 20060101
F03D011/00 |
Claims
1. A wind turbine rotor blade, comprising: a root, a tip, and a
pressure side and a suction side extending between said tip and
said root, said pressure side and said suction side defining an
internal cavity; a plurality of lightning receptors configured
along either or both of said pressure side or said suction side; at
least one looped lightning conductive circuit, said lightning
receptors configured in communication with a respective said
lightning conductive circuit; and, said lightning conductive
circuit comprising terminal ends that extend through said root for
connection of each said terminal end with a grounding system within
a wind turbine; wherein said looped lightning conductive circuit
provides a redundant path to each said lightning receptor for
conducting a lightning strike to ground.
2. The wind turbine blade as in claim 1, comprising a plurality of
said looped lightning conductive circuits, each said lightning
conductive circuit comprising a plurality of said lightning
receptors.
3. The wind turbine blade as in claim 2, wherein said looped
lightning conductive circuits share a common return leg.
4. The wind turbine blade as in claim 1, wherein said terminal ends
are configured for connection to the wind turbine grounding system
within a hub of the wind turbine.
5. The wind turbine blade as in claim 1, wherein said lightning
receptors are configured in series within said looped lightning
conductive circuit.
6. The wind turbine blade as in claim 5, wherein said looped
lightning conductive circuit defines a continuity circuit for said
lightning receptors in series within said looped lightning
conductive circuit.
7. A wind turbine, comprising: a plurality of turbine blades
mounted to a rotor hub, each of said turbine blades comprising a
root, a tip, and a pressure side and a suction side extending
between said tip and said root; at least one of said turbine blades
further comprising a plurality of lightning receptors configured
along either or both of said pressure side or said suction side; at
least one looped lightning conductive circuit, said lightning
receptors configured in communication with a respective said
lightning conductive circuit; and, said lightning conductive
circuit comprising terminal ends that extend through said root and
are each respectively connected to a grounding system within said
hub; wherein said looped lightning conductive circuit provides a
redundant path to each said lightning receptor for conducting a
lightning strike to ground.
8. The wind turbine as in claim 7, comprising a plurality of said
looped lightning conductive circuits within said turbine blade,
each said lightning conductive circuit comprising a plurality of
said lightning receptors.
9. The wind turbine as in claim 8, wherein said looped lightning
conductive circuits share a common return leg.
10. The wind turbine as in claim 7, wherein said lightning
receptors are configured in series within said looped lightning
conductive circuit.
11. The wind turbine as in claim 10, wherein said looped lightning
conductive circuit defines a continuity circuit for said lightning
receptors in series within said looped lightning conductive
circuit.
12. The wind turbine as in claim 11, wherein each said turbine
blade is configured as in claim 11, and further comprising a relay
station within said rotor hub for periodic or continuous continuity
checking of said lightning receptors within each of said blades.
Description
FIELD OF THE INVENTION
[0001] The present subject matter relates generally to wind
turbines, and more particularly to wind turbine rotor blades having
a lightning protection system configured therewith.
BACKGROUND OF THE INVENTION
[0002] Large commercial wind turbines are prone to lightning
strikes and, in this regard, it is a common practice to provide the
turbine blades with lightning receptors spaced along the
longitudinal length of the blade so as to capture and conduct the
strikes to ground. The conventional configuration of these
receptors, however, results in difficult, expensive, and
time-consuming maintenance and diagnostic procedures that typically
require a crane to externally access each receptor. The
conventional configuration does not offer a means to verify the
continuity of the receptors within a blade without accessing and
testing each receptor individually. In addition, the effectiveness
of the receptors depends on the integrity and reliability of a
single conductive path along the blade. Failure (i.e., a break) of
this path renders any upstream receptors essentially useless.
[0003] Efforts have been made to devise alternative lightning
protection systems for wind turbine blades. For example, U.S.
Patent Publication No. 2009/0129927 describes a system that avoids
blade mounted receptors altogether by mounting radially extending
lightning receptors to the rotor hub, with the receptors extending
between the blades. This configuration, however, may result in
increased weight, drag, and noise, and an overall decrease in the
capability of the turbine.
[0004] Accordingly, the industry would benefit from an improved
lightning protection system that utilizes blade-mounted receptors,
yet avoids the disadvantages of conventional receptor
configurations.
BRIEF DESCRIPTION OF THE INVENTION
[0005] Aspects and advantages of the invention will be set forth in
part in the following description, or may be obvious from the
description, or may be learned through practice of the
invention.
[0006] In accordance with aspects of the invention, a wind turbine
rotor blade has a root, a tip, and a pressure side and a suction
side that extend between the tip and root and define an internal
cavity of the blade. A plurality of lightning receptors are
configured along either or both of the pressure side or the suction
side. At least one looped lightning conductive circuit is provided,
which may be within the internal cavity of the blade or external to
the blade. The lightning receptors are configured in communication
with a respective lightning conductive circuit. The lightning
conductive circuit includes terminal ends that extend through the
root for connection of each of the terminal end with a grounding
system within the wind turbine, for example within a hub of the
wind turbine. In this manner, the looped conductive circuit
provides a redundant path to each lightning receptor for conducting
a lightning strike to ground.
[0007] The blade may include a single lightning conductive circuit
with all of the lightning receptors in communication with the
single circuit. In an alternate embodiment, the blade may include a
plurality of the lightning conductive circuits, with each of the
circuits including a plurality of the lightning receptors in
communication therewith. The plurality of lightning conductive
circuits may share a common leg.
[0008] In a particularly unique embodiment, the lightning receptors
are configured in series within their respective looped lightning
conductive circuit. With this embodiment, the looped lightning
conductive circuit may also define a continuity circuit for the
lightning receptors that are connected in series within said looped
lightning conductive circuit.
[0009] The invention also encompasses a wind turbine having one or
more turbine blades configured with a lightning conductive circuit
as described herein.
[0010] In other embodiments, a wind turbine rotor blade has a root,
a tip, and a pressure side and a suction side that extend between
the tip and root and define an internal cavity of the blade. A
plurality of lightning receptors are configured along either or
both of the pressure side or the suction side. At least one
continuity circuit is provided. This continuity circuit may be
configured within the internal cavity of the blade, or external to
the blade. The lightning receptors are disposed in series within a
respective continuity circuit such that an electrical continuity
path defined by the circuit passes through each of the lightning
receptors within the continuity circuit. The continuity circuit
further includes terminal ends that extend through the root and are
accessible for conducting a remote continuity check of the
lightning receptors within the continuity circuit, for example
within a rotor hub on which the blade is mounted.
[0011] The blade may include a single continuity circuit with all
of the lightning receptors in series within the circuit. In an
alternate embodiment, the blade may include a plurality of the
continuity circuits, with each of the circuits including a
plurality of the lightning receptors. The plurality of continuity
circuits may share a common return leg, or may have individual
respective return legs.
[0012] The lightning receptors may be variously configured. In a
particular embodiment, the receptors include spaced apart terminal
posts and the continuity circuit includes a plurality of conductive
wires that interconnect the terminal posts of adjacent lightning
receptors such that the conductive path flows from one of the
terminal posts, through the lightning receptor, and out from the
other terminal post. In still a further embodiment, the lightning
receptors have a single terminal post and the continuity circuit
includes a plurality of conductive wires that interconnect the
single terminal posts of the multiple receptors such that a first
one and a second one of the conductive wires are mounted to each
single terminal post with a dielectric insulating material
therebetween.
[0013] In unique embodiments, all or part of the continuity circuit
may also define all or a portion of a lightning conductive path
that connects the lightning receptors in series. For example, in
one embodiment, the entire continuity circuit defines a lightning
conductive path and, in this manner, a redundant lightning
conductive path is provided for each lightning receptor in the
event of a break in the continuity circuit at any one location.
[0014] The present invention also encompasses any configuration of
a wind turbine having one or more blades with a continuity circuit
as described herein.
[0015] The present invention also encompasses various method
embodiments for verifying functionality of lightning receptors in a
wind turbine blade by defining one or more continuity circuits
wherein each of the lightning receptors configured on the wind
turbine blade is included within at least one continuity circuit.
The method includes configuring the lightning receptors in series
within a respective continuity circuit such that an electrical
continuity path within the circuit passes through each lightning
receptor within the continuity circuit. A continuity check is
conducted at terminal ends of the continuity circuit. This check
may be done on a periodic or continuous basis.
[0016] In a particular method embodiment, a plurality of the
continuity circuits are defined for an individual respective
turbine blade, with each continuity circuit comprising a plurality
of lightning receptors. A common return leg may be provided for the
plurality of circuits, or each circuit may have its own respective
return leg.
[0017] Another method embodiment may include configuring at least
one leg of the continuity circuit as a lightning conductive
path.
[0018] These and other features, aspects and advantages of the
present invention will become better understood with reference to
the following description and appended claims. The accompanying
drawings, which are incorporated in and constitute a part of this
specification, illustrate embodiments of the invention and,
together with the description, serve to explain the principles of
the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0019] A full and enabling disclosure of the present invention,
including the best mode thereof, directed to one of ordinary skill
in the art, is set forth in the specification, which makes
reference to the appended figures, in which:
[0020] FIG. 1 illustrates a perspective view of a conventional wind
turbine;
[0021] FIG. 2 illustrates a cross-sectional view of a rotor blade
with a plurality of lightning receptors connected in series in a
continuity circuit;
[0022] FIG. 3 illustrates the embodiment of FIG. 2 with a leg of
the continuity circuit also configured as a lightning conductive
path;
[0023] FIG. 4 illustrates a cross-sectional view of an embodiment
of a lightning receptor;
[0024] FIG. 5 illustrates a cross-sectional view of an alternative
embodiment of a lightning receptor;
[0025] FIG. 6 is a cross-sectional view of an embodiment of a
looped lightning conductive path within a wind turbine rotor blade
with the lightning receptors of FIG. 4;
[0026] FIG. 7 is a cross-sectional view of still another
alternative embodiment of a looped lightning conductive path within
a wind turbine rotor blade with the lightning receptors of FIG.
5;
[0027] FIG. 8 is a cross-sectional view of an embodiment with
multiple looped lightning conductive paths within a wind turbine
rotor blade;
[0028] FIG. 9 is a cross-sectional view of an embodiment of
multiple continuity circuits within the wind turbine blade with one
leg of each circuit also functioning as a lightning conductive
path;
[0029] FIG. 10 is a cross-sectional view of an embodiment having
multiple continuity circuits that share a return leg; and,
[0030] FIG. 11 is an illustration of a wind turbine with rotor
blades in accordance with aspects of the invention.
DETAILED DESCRIPTION OF THE INVENTION
[0031] Reference now will be made in detail to embodiments of the
invention, one or more examples of which are illustrated in the
drawings. Each example is provided by way of explanation of the
invention, not limitation of the invention. In fact, it will be
apparent to those skilled in the art that various modifications and
variations can be made in the present invention without departing
from the scope or spirit of the invention. For instance, features
illustrated or described as part of one embodiment can be used with
another embodiment to yield a still further embodiment. Thus, it is
intended that the present invention covers such modifications and
variations as come within the scope of the appended claims and
their equivalents.
[0032] Referring to the drawings, FIG. 1 illustrates a perspective
view of a horizontal axis wind turbine 10. It should be appreciated
that the wind turbine 10 may be a vertical-axis wind turbine. In
the illustrated embodiment, the wind turbine 10 includes a tower
12, a nacelle 14 mounted on the tower 12, and a rotor hub 18 that
is coupled to the nacelle 14. The tower 12 may be fabricated from
tubular steel or other suitable material. The rotor hub 18 includes
rotor blades 16 coupled to and extending radially outward from the
hub 18. As shown, the rotor hub 18 includes three rotor blades 16.
However, in an alternative embodiment, the rotor hub 18 may include
more or less than three rotor blades 16.
[0033] The rotor blades 16 may generally have any suitable length
that enables the wind turbine 10 to function according to design
criteria. For example, the rotor blades 16 may have a length
ranging from about 15 meters (m) to about 91 m. However, other
non-limiting examples of blade lengths may include 10 m or less, 20
m, 37 m, or a length that is greater than 91 m. The rotor blades 16
rotate the rotor hub 18 to enable kinetic energy to be transferred
from the wind into usable mechanical energy, and subsequently,
electrical energy. Specifically, the hub 18 may be rotatably
coupled to an electric generator (not illustrated) positioned
within the nacelle 14 for production of electrical energy.
[0034] Referring to FIGS. 2 through 5 in general, a wind turbine
rotor blade 16 is provided having a root 30, a tip 32, a pressure
side 34, and a suction side 36. The pressure side 34 and suction
side 36 extend between the root 30 and tip 32 and define an
internal cavity 38 for the blade 16. A plurality of lightning
receptors 40 are configured along either or both of the pressure
side 34 or suction side 36. For example, in the embodiment
illustrated in figures, a plurality of the lightning receptors 40
are provided on each of the pressure side 34 and suction side 36.
In an alternative embodiment, the lightning receptors 40 may be
provided on only one of the sides 34, 36. In the embodiments
wherein the lightning receptors 40 are configured in series in a
continuity circuit, as in FIGS. 2 and 3, each receptor 40 is
uniquely configured in series with the wires or other conducting
members that define the continuity circuit, as described in greater
detail below.
[0035] The lightning receptors 40 may be variously configured
within the scope of the invention, and include any metal or
metalized component (i.e., a metal screen, a metal rod or tip, and
the like) mounted on the pressure or suction sides 34, 36 of the
blade for the purpose of conducting lightning strikes to
ground.
[0036] Referring to FIG. 2, at least one continuity circuit 42 is
provided. This circuit is illustrated in the figures as within the
internal cavity 38 of blade 16. In other embodiments, the circuit
may be defined by components that are embedded in the blade, or are
external to the blade 16, for example along the outer surfaces of
the blade 16.
[0037] The lightning receptors 40 are disposed in series within a
respective continuity circuit 42 such that an electrical continuity
path defined by the circuit 42 passes through each of the lightning
receptors 40 that is contained within the continuity circuit 42.
For example, referring to FIG. 2, the lightning receptors 40 are
all configured within a single continuity circuit 42. The receptors
40 are daisy-chained together with a plurality of conductive wires
(or other conductive members) 41 of suitable size and gauge for
conducting a continuity check of all of the receptors 40 within the
circuit 42 from the terminal ends 44 of the circuit. It should be
understood that the conductive members 41 may also include any
configuration of the blade structure within the circuit, such as
carbon spar caps, trailing serrations, leading edge protectors,
fairings, and so forth. As is well known, the continuity meter (or
other continuity-check device) is connected to the terminals 44 and
current is supplied to the circuit 42. The measure of return
current indicates the continuity of the elements within the circuit
42. Thus, the continuity of each of the lightning receptors 40
within the circuit 42 is verified. If any one of the lightning
receptors 40 has been damaged or failed so as to define a break
("open") within the circuit 42, then the continuity circuit check
will fail (indicate an open circuit), which indicates to the
maintenance technician that at least one of the lightning receptors
40 within the particular blade 16 has failed and needs repair or
replacement.
[0038] The embodiment of FIG. 3 is similar to the embodiment of
FIG. 2, with the exception that the conductive members 41 that
connect the lightning receptors 40 in series have a gauge suitable
for defining a conductive leg 48 for transmitting a lightning
strike on any one of the receptors 40 to ground via connection of
the conductive terminal 45 to the wind turbine's ground system, as
described further below. The conductive leg 48 is emphasized in
FIG. 3 by the heavier lines that interconnect the lightning
receptors 40. The return leg 46 of the continuity circuit 42 is
emphasized by the lighter, hashed line and is generally not
suitable as a lightning conductor. The conductive leg 48 is,
however, also suitable for conducting the continuity check of the
series-configured lightning receptors 40, as discussed above.
[0039] The series-connected lightning receptors 40 may be variously
configured within the scope and spirit of the invention. In the
embodiment of FIGS. 2 and 3, each receptor 40 has a double-post
configuration, as in the embodiment of FIG. 5. Referring to FIG. 5,
the receptor 40 includes a receptor plate 50 that is mounted on the
exposed surface of the pressure side 34 or suction side 36.
Conductive posts 52 configured on an underside of the plate 50
extend through holes (not shown) in the pressure side 34 or suction
side 36 into the internal cavity 38 of the blade 16. A first
conductor 55 (a wire or cable depending on whether the conductor 55
is also part of a lightning conductive leg) is attached to a first
one of the post 52. A second wire/cable 57 is attached to the other
post 52. The posts 52 may be threaded members and nuts 54 may be
conveniently used to securely attach the terminal ends of the
wire/cables 55, 57 to their respective post 52, as depicted in FIG.
5.
[0040] It can be appreciated from FIG. 5 that, for a continuity
check of the lightning receptor 40, current flows from the first
wire/cable 55, through the receptor 40 (particularly the plate 50)
to the opposite post and connected wire/cable 57. From cable/wire
57, the current flows to the next lightning receptor 40 in the
series. A break or other malfunction of the lightning receptor 40
that creates an open in the circuit 42 will cause the circuit check
to fail. The embodiments of FIGS. 2 and 3 depict each of the
lightning receptors 40 as the double-post configuration of FIG.
5
[0041] FIG. 4 illustrates an alternative embodiment of a lightning
receptor 40 wherein a single post 56 extends from the underside of
the receptor plate 50. The first 55 and second 57 wire/cables are
secured to the post 56 with a nut 54. An insulating dielectric
material 58, such as a dielectric washer, separates the terminal
ends of the wire/cables 55, 57 to prevent the wire/cables from
shorting and eliminating the receptor 40 from the continuity
circuit. In an alternate embodiment, the terminal ends are simply
spaced apart on the post 56, for example by nuts, and the
dielectric material is dispensed with. In this single post 56
configuration, the conductive post 56 is used to convey current
from one of the wire/cables to the other wire/cable 55, 57.
[0042] Each blade 16 may include a single continuity circuit 42, as
depicted in the embodiments of FIGS. 2 and 3, with each of the
lightning receptors 40 configured in series within the single
circuit 42. In an alternative embodiment depicted for example in
FIG. 9, the blade 16 includes a plurality of continuity circuits
42, with each of the lightning receptors 40 configured in one of
the respective circuits 42. For example, referring to FIG. 9, the
lightning receptors 40 mounted on the pressure side 34 of the blade
16 are contained within a first continuity circuit 42 and the
lightning receptors 40 mounted on the suction side 36 are
configured in series in a second continuity circuit 42. The portion
of the circuit 42 that connects the receptors 40 in series in each
of the circuits 42 is also configured as a conductive leg 48. Each
of the circuits 42 includes terminals 44 and 45, with terminal 45
being connected to the wind turbine's ground system, as discussed
above.
[0043] In still a further embodiment as depicted in FIG. 10, the
blade 16 may have multiple continuity circuits 42 that share a
common return leg 46. The continuity check can be conducted with
the common return leg 46 merely by switching between the terminals
45 when conducting the respective checks.
[0044] Referring to FIGS. 6 and 7 as an example, the present
invention also encompasses blades 16 wherein the entire continuity
circuit 42 is defined by conductive members that are also suitable
for conducting a lightning strike to the turbine's ground system.
For example, referring to FIG. 6, the single continuity circuit 42
that interconnects the receptors 40 in series also defines a looped
lightning conductive circuit 60 having terminal ends 62. Each of
the terminal ends 62 may be connected to the wind turbine's ground
system and may also be used for conducting a continuity check, as
discussed above. In other words, the continuity circuit 42 and the
looped lightning conductive circuits 60 are defined by the same
conductive members, including the receptors 40.
[0045] FIG. 7 is similar to the embodiment of FIG. 10 discussed
above wherein the multiple continuity circuits 42 share a common
return leg 46. In the embodiment of FIG. 7, the common return leg
is defined by a lightning conductive leg 64. Thus, each of the
continuity circuits 42 also defines a lightning conductive circuit
60 having multiple terminal ends 62. The ends 62 also serve as the
terminal ends for the continuity circuits 42.
[0046] The terminal ends 44, 45, 62 (whether intended for the
continuity circuit 42 or lightning conductive circuit 60, or both)
extend through the blade root portion 30, as indicated in the
various figures, for access within the rotor hub 18 to which the
individual respective turbine blades 16 are mounted. In this
manner, a maintenance technician may gain access to the respective
terminal ends within the rotor hub 18 for conducting the continuity
checks of the respective circuits 42 from within the rotor hub.
[0047] It should be appreciated that the present invention also
encompasses wind turbine blades that include at least one looped
lightning conductive circuit 60 configured with the internal cavity
38 of the blade 16, with the lightning receptors 40 configured in
communication with a respective lightning conductive circuit 60
(and not necessarily in series within the circuit 60). Referring to
FIGS. 6 through 8, each of the lightning conductive circuits 60
includes terminal ends 62 that connect to the wind turbine's
lightning ground system, as discussed in greater detail below with
respect to FIG. 12. Thus, the looped lightning conductive circuit
60 provides a redundant ground path to each of the individual
receptors 40 for conducting a lightning strike to ground. Referring
to FIG. 6 as an example, it can be readily appreciated that a break
or "open" in any one of the sections of the lightning conductive
circuit 60 between the respective lightning receptors 40 does not
result in isolation of any one of the receptors 40. An alternate
ground path is established for the receptors 40 via the alternate
loop portion of the circuit 60. For example, referring to FIG. 6, a
break 80 in the portion of the circuit 60 indicated in the figure
does not render any of the lightning receptors 40 ineffective. The
receptors 40 on the pressure side 34 to the left of the break 80
are still in communication with the turbine's ground system by way
of the upper terminal end 62. The receptor 40 to the right of the
break 80 is in electrical continuity with the lower terminal end
62, as are all of the receptors 40 along the suction side 36 of the
blade.
[0048] It should be understood that any portion of the lightning
conductive circuit 60 may include existing blade structure within
the circuit, such as carbon spar caps, trailing serrations, leading
edge protectors, fairings, and so forth.
[0049] Referring to FIG. 11, it should be appreciated that, in the
embodiments of the invention drawn particularly to the
looped-configuration of a lightning conductive circuit 60 within
the blade 16, it is not a requirement that the receptors 40 are
configured in series within the loop 60 (as in the embodiments of
FIGS. 6 through 8). In the embodiment of FIG. 11, the lightning
conductive circuit 60 is defined within the internal cavity 38 by a
continuous looped conductor having terminal ends 62. The individual
lightning receptors 40 are connected in a T-connector configuration
with a branch connector 63, and are thus not in series within the
circuit 60. It should, however, be appreciated that the
configuration of the circuit 60 depicted in FIG. 11 cannot be used
to separately conduct a continuity check of the receptors 40, as is
possible with the embodiments of FIGS. 6 through 8, as discussed
above.
[0050] Each blade 16 may include a single lightning conductive
circuit 60, as illustrated in FIG. 6, or multiple circuits 60 as
illustrated in FIGS. 7 and 8. In the embodiment of FIG. 7, the
separate circuits 60 share a common return leg 64, whereas in the
embodiment of FIG. 8, each of the circuits 60 has an individual
respective return leg 64. Each of the terminal ends 62 (in all of
the embodiments of FIGS. 6 through 8) is individually connected to
the wind turbines' ground system in the rotor hub 18. Thus, each
looped lightning conductive circuit 60 provides redundant ground
paths for the receptors 40 within the respective loop 60.
[0051] It should be appreciated that the invention also encompasses
any manner or configuration of wind turbine 10 having blades 16
utilizing any one of the aspects described herein. For example,
referring to FIG. 12, the wind turbine 10 includes at least one
turbine blade 16 having a plurality of lightning receptors 40
configured along either or both sides of the blade 16. In the
illustrated embodiment, each of the blades 16 is configured in a
similar manner. Each blade 16 includes at least one looped
lightning conductive circuit 60 configured within the internal
cavity of the blade, with the lightning receptors 40 of each blade
configured in communication with a respective lightning conductive
circuit 60. As discussed above, the blade 16 may include multiple
circuits 60. The respective lightning conductive circuits 60
include terminal ends that extend through the root portion of the
blades 16 and are individually connected to a grounding system
within the rotor hub 18. The grounding system may be variously
configured, as is well known in the art. For example, the grounding
system may include any manner of the wind turbine's machinery or
support structure, including blade bearings, machinery bed plates,
tower structure, and the like, that defines any suitable ground
conductive path 68 from the blades 16, through the tower 12, to a
ground rod 70 via a ground cable 72, or other suitable electrical
ground path.
[0052] In a desirable embodiment as discussed above, the individual
lightning receptors 40 are configured in series within the
lightning conductive circuit 60 so that the circuit 60 may also
function as a continuity circuit 42 for verifying the continuity of
the individual receptors 40. In this regard, a relay station 66
defining any manner of suitable access or switching capability to
the terminal leads 62 may be supplied within the rotor hub 18,
whereby a maintenance technician may access the respective stations
for conducting the continuity circuit checks, as described above.
In other embodiments, one or more relay stations 66 may provide for
automatic electronic switching between the various circuits 42 in a
periodic or continuous monitoring or diagnostic procedure.
[0053] This written description uses examples to disclose the
invention, including the best mode, and also to enable any person
skilled in the art to practice the invention, including making and
using any devices or systems and performing any incorporated
methods. The patentable scope of the invention is defined by the
claims, and may include other examples that occur to those skilled
in the art. Such other examples are intended to be within the scope
of the claims if they include structural elements that do not
differ from the literal language of the claims, or if they include
equivalent structural elements with insubstantial differences from
the literal languages of the claims.
* * * * *